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Objects in images could be crash debris, say oceanographers

Melanie Kembrey

Eyes in the sky: Academics say it is unlikely that the floating objects spotted in the southern Indian Ocean came from ships. Photo: Fairfax Graphics

Large floating objects are extremely unusual in the southern Indian Ocean and there probably is ''no common explanation'' for those captured in satellite imagery, marine experts say.

Shipping containers, beds of seaweed, trees and trawling nets were unlikely given the length and apparent intact state of the objects identified from satellite images about 2500 kilometres off the coast of Perth, James Cook University marine scientist Robin Beaman said.

''The scale is important and until we see it up close we can't discount that it might be from the crash site,'' Dr Beaman said.

Pilots aboard a Royal New Zealand Air Force P-3K2 Orion aircraft searching the southern Indian Ocean for the plane on Saturday. Photo: Reuters

''Even big freight containers, the biggest ones, are not as long as the object in the images. The scale is pretty significant.''

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University of Western Sydney oceanographer Charitha Pattiaratchi said the area where the images were captured and where wooden pallets and straps were seen was outside normal shipping lanes and distant from circular currents in which waste often accumulated.

''Usually things that have been in the ocean for a long time are either under the surface or sink or break down into much smaller pieces,'' Professor Pattiaratchi said.

''To see a large object like that, then certainly it is credible [it is wreckage]. It is extremely unusual.

''Each of the oceans has what's called a big gyre [circular current] and usually any debris goes around this gyre and sometimes they accumulate in the centre, but the search area is thousands of kilometres from the region and we are in a different system.

''The southern Indian ocean is an area which is relatively free of debris.''

Finding the objects should be a priority as technology could then be used to determine how currents had moved the objects during the past two weeks, Dr Beaman said.

He said the marine debris could have floated hundreds of kilometres away from where it started, including off the coast South Africa or South America.

''If they were actually able to get some eyes on the objects really quickly it would be obvious whether they had been discarded a long time ago or whether it had been in the ocean for some time,'' Dr Beaman said.

''The longer they spend in the ocean, they get colonised by barnacles and the like. Recovery would be the best outcome because what they can do then is use hydrodynamic models to hindcast a current float, to track back, and narrow it down to a crash site.''

It would then be a matter of searching underwater at that spot for the black box and heavier debris that would have immediately sunk, he said. ''I wouldn't rule anything out entirely because like anything in the ocean, for every rule there is an exception.''

University of Sydney UNESCO chair in marine science Elaine Baker said there was such a ''huge amount of rubbish'' in the ocean, that it was often hazardous for ships. ''But the thing is the ocean is so vast, coming across something really large is probably quite rare,'' she said.